Controlling mechanism



Nov. 4

D. V` STEWART CONTROLLING MECHANI SM 1923 3 Sheets-Sheet 1 Filed July19,

Nov.'4 1924. V 1,514,268

. x D. v. STEWART CONTROLLING MECHANI SM Filed July 19, 1923 3Sheets-Sheet 2 FORWARD Nov. 4 1924. l

D. V. STEWART CONTROLLING MECHANI SM 'nleg July 19, 192s 3 Sheets-snee t3 'making a short circui Patented Nea4, 1924.

1,514,268 TES PATENT oFFlcl-z.

nAvIn v. STEWART, or COLUMBIANA, omo.

GONTROLLING MECHANISML Application led July 19, 1923.' Serial No.652,586.

To all whom it'may concern: Be it known that I, DAVID V.. STEWART, acitizen of the United States, and resident of Columbiana, in the countyof Columbiana' and State of Ohio, have invented certain new and usefulImprovements in Controlling Mechanisms, of which the following is aspecification.

Thisinvention relatesto electric furnaces and more particularly tomeans-'for automatically controlling the low of electric current to theelectrodes of such furnaces. One object of the present invention is toprovide suitable apparatus adapted to automatically break the electricalcircuit to the electrodes when the furnace is tilted.

Heretofore hand operated means have been provided for breaking theelectrical circuit. to the electrodes when desired, 'and Ythe operatorshave been required to break .the electrode circuit prioito tilting thefurnace. .However, the operators at times would tilt the furnace withoutbreaking the lectrode circuit and at such time's there is anger of the'electrodes or their connections touching the cables which hold theladle, positioned to receive `the metal, and which burns the cable anddrops the ladle; v The dropping o f a .ladle having moltenme'taltherein, as is well known, generally results in serious accidents toemployes.

Again, when a furnace has been emptied and is tilted back empty, theoperatorsfassume that the electrode circuit has been broken and when ithas. not theyhave been knownto have gotten shockedfcausing more or lessserious results. With thepresent invention all of the aboveobjectionable and serious results are eliminated, since-the electrodecircuit will he automatically broken' when the furnace is tilted.

In the drawings, Figure 1 is a somewhat diagrammatic side elevation ofan electric furnace of the class to which my invention pertains. Figure2 is a wiring diagram illustrating the preferred embodimentof myinventlon.

Figures 3 and 4 are ywiring diagrams illustrating modifications of myinvention.

Referrin particularly to the drawings, the numera .2 designates the bodyof the furnace as a whole, which `is of well known construction, and isprovided with back and front ports closed by doors 3 and 4,respectively. Rockers k5 are mounted on the bottom of the body 2 andrest on the curved upper face of supporting base 6. Theyfurnace 1sadapted to be rocked or tilted by one or more cranks 7 which are securedto a shaft 8 and connected to the furnace body y2 by links 9. The shaft8 is adapted to be rotated by a motor lOthrough gears-11 and 12. It willbe understood that this invention 1s not llmited to the specific form offurnace described above, but is adapted to any form of tilting electricfurnace, the form shown being used to illustrate the invention becauseof its simplicity.

A plurality of electrodes 14, 15 and 16 are mounted in the usual mannerin the furnace body 2 and are adapted to receive electric currentthrough the wires or cables 17, 18 and 19.

lReferring to the wiring diagram of Figure 2, the numerals 20, 21 and 22designate the main power lines to the furnace electrodes, and thenumerals 23 and 24 designate power lines leading to the tilting motor 10and from which the control circuits are conveniently run in apparatusmade as shown in the drawings.

The lines 20, 21 and 22 lead-to a main oil Y switch or interrupter 25,which is adapted lto break the circuit to the furnace electrodes Awhichare connected to the switch 25 by .means of wires 17, 18 and 19. Theswitch 29, the other side being connected to the positive line 24 andenergizing coil 29. By energizing coil 29, the plunger 3() in theauxiliary relay is raised, making ay circuit between contact points 31and 32, Contact 32 is connected to the positive line 24 and contact 3lis connected to the closing coil 33 .for the switch 25, the other sideof the coi being connected to the negative line 28, thus energizing thecoil 33 and closing the switch 25. At the same time auxiliary switch 34closes contacts 35 and 36 and `opens contacts 37 and 38, thus placing apositive potential from line 24 on one side o red light 39, the otherside being connected to the negative line 23 through fuse 40 andresistance 41,

thus Ilighting the red light 39, which form's a circuit in the'usualmanner, the pushibutton 42 is closed, thus connecting points 43 and 44and putting negative potential from line 23 on one side of'trp coil 45for switch 25, the other side of the coil being connected tc. point :36,and'thence through switch 34 to point 37 and. positive line 2,4. The conlight 47.

45 is thus energized and opens the switch 25, which breaks the circuittothe electrodes 14, 15 and 16. At the same time, auxiliary In case ofan overload on the electrode, circuit may be broken through'. the switch25 by the overload relays 50. If the elec trode circuit exceeds acertain predetermined value, coil or coils 51 in the. over-p load relaysA50 will be suliciently energized,

due to the transformers 52, to actuate contact or contacts 54, so as tocause the closing of the positive and negativelines 23y and 24 acrossthe trip coil 45, in the same sequence as in closing the push button 42,

as described above, thus tripping the main oil vswitch 25 and opening`the electrode circuit and lighting green light 47. e

The vabove control of the electrode cir-.

cuit, it will be noted, either depends uponl the operator pushing thebutton 28 or upon an overload, and if the operator omits to operate thebutton 28 when tilting the furnace the electrode circuit will remainunbroken.

In order to positively prevent the electrode circuit remaining on duringthe tilting of the furnace, I have provided acontrol for saidcircuit,.which is coupled with? the controller for the tilting motor.,10. A

standard controller is provided for controlling the circuit to the motorv1.0, and. it is provided with additional contacts 56,'.

57, 58 and 59, the remaining contacts, not being of necessity in thesame arrangement, are not shown. ,'When the controller55 isv I position,power is applied tothe motor 10.

to move it in the desireddirection toA tilt the furnace. Assume that.the controller 55 be moved to the forward posltion,` xfnakilr'' V an.

contact between contacts 56 and 57j' vpoints 60 and 61.. When vthiscontactf iis" made, negative potential 'is supplied tol point 60 fromlie 23, thence'v through contacts 56 and 57 and point 61, to trip coil.45,

from trip coil 45 to point 36,- through switch 34 to point 35 topositive line 24. The

oil switch 25 is thus trip ed and the electrede circuit broken,l an thegreen. light circuit. is made as explained in the manual operatlon. Thesame result is obtained when the controller'55 is moved to the reand 61the this modified control a normally open limit switchf65 is secured onthe base 6 of the furnace (see Figure 1) and 'serves to make the circuitthrough lines'66 and 67, which are the same lines closed by the contacts56-57 and 58--59 on the'controller 55 of Figure 2. In o eration, whenthe furnace tilted theswltch 65 will be operated to close points 69 and70, thus putting negative potential from supply line 23 on one side oftripfcoil 45, the other side being conynected'to 'point 36, throughswitch 34 to point '35, and thence to the positive line 24, thusenergizing the trip coil 45 and operating the main' switch orinterrupter 25. The circuit to the red light is also broken and thecircuit made to the green light, as heretofore described.

Referring now to theF modified construction of Figure 4, a vnormallyclosed limit 4switch 69, which controls a circuit from the lines 23 and24, is substituted for the switch 65 of Figure 3 and operaaltes tonormally hold an ,auxiliary relay 70 open. The relay 70 is provided witha plunger 71gadapt'edl to close across contact points 72 andlz73connected tok lines 66 and 67, respectively:-l` lWhen the furnace istilted in either -direction theswitch 69 will VVbe o erated toppen thecircuit to the relay 0 and, therefore, the plunger 71 will drop .closinga circuit through points J72 and 73 and wire 66 and 67 with exactly thesame .'esultsaswhen they switch 65 is closed or contacts 561457 or 5S-59are closed inthe l ,jotherfcontrols moved to either the forwardorvreverse. ffi` l l *provideanvutoiatic control for breaking The.mainfeature of the invention is to thef'electrode'fcircuit when thefurnace is have` specically I described cerinf embodiments. of myinvention, I do snot Wight() 'be limited thereto, since various changes,and modifications may be made without departing from the scepe ofmyinvenltion as defined in the appen ed claims.

I C :e

furnaceghaving at least one electrode, landi a-sOmoe of electriccurrentfor said elec- 1. The combination with atilting electric trode,of means for automatically `breaking the circuit to saidv electrode whentilting said furnace.

2. The combination with a tilting electric furnace havin at least oneelectrode, and a source of e ectric current for said electrode, of aninterrupting device controlled by an individual control circuit andadapted to interrupt the ow of electric current to said electrode, andmeans for automatically making said control circuit to cause said deviceto interrupt the circuit to said electrode when tilting said furnace.

3. The combination with a tilting electric -furnace having electricallyoperated tilting mechanism and at least one electrode, an a source ofelectric current for said electrode, of means for controlling the flowof electric current to said tilting mechanism, and an interruptingdevice controlled by an individual control circuit adapted tointerruptthe flow of electric current to said electrode, and meanscontrolled by said first named means for making and breaking the controlcircuit to said interrupting device.

4. The combination Withan electric fur nace having a furnace bodymounted for tiltin about a fixed axis, means for tilting said furnace,an electric motor for operating said means, a source of electric currentfor said motor, at least one electrode mounted in said furnace, and asource of electric current to said electrode, of an interrupting devicefor interrupting the :dow of current to said electrode, and means forautomatically operating said interruptor to break the flow of current tosaid electrode when tilting said furnace.

5. The combination with. an electric furnace having a furnace bodymounted for tilting about a fixed axis, means for tilting said furnace,an electric motor for operating said means, a source of electric currentfor said motor, at least one electrode mounted in said furnace, and asource of electric current to said electrode, of an interrupting devicefor interrupting the How of current to ,said electrode, said devicebeing operated by a separate control circuit, and a controller forcontrolling the flow of electricV current to said motor for tilting saidfurnace and for making and breakin said control circuit to saidinterrupting evice,

said controller being adapted to make the i control circuit to saidinterruptin device when moved to either its forwar or reverse position.

In testimony whereof I have hereunto signed my name.

' DAVID V. STEWART.

